Closed-loop adaptive power control for adjusting bandwidth in a mobile handset transmitter

ABSTRACT

A mobile handset is arranged with an adaptive power controller to controllably adjust transmit power. The adaptive power controller is coupled to a power amplifier module to form a closed feedback loop. The adaptive power control module includes a first shifter, a first sealer, an accumulator and a hold element. The first shifter and first sealer receive respective bandwidth control signals and an error signal. The first shifter and first sealer generate a modified error signal that is forwarded to and filtered by the accumulator and the hold element to generate a power control signal. The power control signal, which is generated the radio frequency subsystem of the handset can quickly and accurately track rapid changes in transmit power.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to the following U.S. provisionalapplications titled “Closed Loop Adaptive Power Control Using a VoltageReference,” having Ser. No. 61/027,073; “Closed Loop Constant-BandwidthPower Control For Logarithmic Control Characteristics,” having Ser. No.61/027,078 and “Closed Loop Compensated-Bandwidth Power Control Using aVoltage Reference, having Ser. No. 61/027,081, all filed on Feb. 8,2008, and which are entirely incorporated herein by reference.

BACKGROUND

This invention relates generally to transceiver architecture in awireless mobile communication device.

Radio frequency (RF) transmitters are found in many one-way and two-waycommunication devices, such as mobile communication devices, (cellulartelephones), personal digital assistants (PDAs) and other communicationdevices. A RF transmitter must transmit using whatever communicationmethodology is dictated by the particular communication system withinwhich it is operating. For example, communication methodologiestypically include amplitude modulation, frequency modulation, phasemodulation, or a combination of these. In a typical global system formobile communications (GSM) mobile communication system using narrowbandtime-division multiple access (TDMA), a Gaussian minimum shift keying(GMSK) modulation scheme is used to communicate data.

The deployment of new wireless systems presents unique challenges tomobile handset designers. In order to reap the full benefit of expandedcapacity and increased data bandwidth, the new handsets must work onboth the new systems as well as the old. One of these new systems hasbeen named Enhanced Data Rates for GSM Evolution (EDGE). The EDGEstandard is an extension of the Global System for Mobile Communications(GSM) standard.

The EDGE standard increases the data rate over that available with GSMby sending more bits per RF burst. More bits are sent in EDGE by using amodulation scheme based on 8-phase shift keying (8PSK), which providesan increase over GSM's Gaussian minimum shift keying (GMSK) modulationformat. In the EDGE modulation scheme, the 8PSK constellation is rotated⅜ radians every symbol period to avoid problems associated with zerocrossings. In contrast to GMSK's constant amplitude envelope, the EDGEmodulation scheme results in a non-constant amplitude envelope. Thisnon-constant amplitude in the output signal presents some difficultieswith regard to RF power control.

During multi-slot operation of a mobile handset transmitter using 8PSKmodulation, the power of the modulated radio-frequency (RF) signal isrequired to ramp-up to a desired power level for a set period of timeduring which the handset transmits encoded data symbols. After thetransmission has completed, the power of the modulated RF signal isrequired to return or ramp down to an off power level. The ramp-up andramp-down must be accomplished without adversely affecting time andfrequency parameters defined by the EDGE communication standard.

One conventional approach to power control generates a signal that isused to controllably adjust the gain of a variable gain amplifierlocated in series with a linear power amplifier. For polar looptransmitter architectures, which are already operating near saturationin 8PSK mode, power control has been accomplished through poweramplifier bias controls. These conventional power controllers requireintegrated circuit space, increase the power budget of the mobilehandset and for some conditions require a longer time than thatavailable to meet frequency spectrum requirements.

Another approach is introduced in U.S. Patent Application Publication2005/0249312 to Bode et al. (the '312 publication). The '312 publicationdescribes a digital modulator that introduces dips in the envelope ofthe I/Q signal between adjacent time intervals or bursts. A dip-shapedwaveform is multiplied with each of the I and Q waveforms to introducethe dips. A pulse-shaping filter is used with the dip-shaped waveform toobtain the desired result in the envelope of the I/Q signal. Thissolution requires additional memory to store the dip waveform andintegrated circuit space to implement the pulse-shaping filter.

In addition to the EDGE standard, some mobile networks communicate usinga code division multiple access (CDMA) standard. In a communicationsystem using CDMA, a base station transmits control messages and voicetraffic to the mobile handsets on a forward link. The mobile handsetssend control messages and voice traffic to the base station on aseparate reverse link. While, both the forward and reverse links requirepower control, the main need for power control arises in the reverselink.

The reverse link requires power control primarily to solve the“near-far” problem. In a CDMA communication system, all handsetstransmit on the same frequency channel at the same time but withdifferent codes. Therefore, one handset's signal may interfere with theothers. A particular mobile's received signal quality at the basestation is inversely proportional to the power of the interference fromother mobile handsets. The near-far problem arises when two mobilehandsets transmit at the same power but at different distances from thebase station. Due to different propagation losses, the transmissions canarrive with very different received power levels. The mobile handsetnearer the base station, which has a high received signal power, greatlyinterferes with a more distant mobile handset, which under somecircumstances may not be detected.

Power control in the reverse link also deals with the rapidly changingattenuation characteristics of multipath fading channels common in urbanenvironments. In these environments, the received power of a typicalwireless channel varies dramatically with time for moving handsets andmultipath characteristics.

To solve problems encountered in urban environments, an open-loop powercontrol algorithm ensures that the received power levels of all handsetsare the same at the base station. The algorithm does this by controllingthe transmit power from each of the separate mobile handsets. Ingeneral, a particular handset is commanded to transmit at a higher powerlevel when their received power is low, such as when they are far fromthe base station. Additionally, handsets are commanded to transmit at alower power level when their received power is high, such as when theyare near the base station.

To control power in this manner, the algorithm regularly monitors thereceived power of each mobile handset and commands each handset toadjust its respective transmit power to achieve predefined performancelevels, such as frame error rate (FER). The base station commands eachof the handsets to set their transmit power levels with predefined stepsizes for making rapid changes. This open-loop control scheme is unableto respond to rapid power changes such as those that occur due to theuse of DC-to-DC converters in enhanced power amplifiers.

SUMMARY

An embodiment of a mobile handset includes a power amplifier module andan adaptive power controller. The power amplifier module includes apower amplifier and a power detector. The power amplifier receives atransmit signal and a power control signal and generates an amplifiedtransmit signal. The power detector is configured to generate a detectoroutput that is responsive to the amplified transmit signal power fromthe mobile handset. The adaptive power controller is coupled to thepower amplifier module and forms a closed control loop. The adaptivepower controller includes a first shifter, a first scaler, anaccumulator and a hold element. The first shifter and the first scalerreceive respective bandwidth control signals and together generate amodified error signal responsive to an error signal generated from atarget power level and the detector output. The accumulator and holdelement integrate and filter the modified error signal to generate thepower control signal.

An embodiment of method for adaptive power control for adjustingbandwidth in a mobile handset includes the steps of using a powerdetector to detect an output power level generated by a power amplifier,generating an error signal responsive to a target power level and theoutput power level in a radio frequency sub-system of the mobilehandset, and applying a bandwidth control signal to the error signal togenerate a modified error signal in a closed control loop of an adaptivepower controller in the mobile handset, the adaptive power controllercontrollably forwarding one of the modified error signal or a code togenerate a power control signal in response to a desired range oftransmit power.

The figures and detailed description that follow are not exhaustive. Thedisclosed embodiments are illustrated and described to enable one ofordinary skill to make and use the circuits for closed loop powercontrol in a mobile handset. Other embodiments, features and advantagesof the circuits for closed loop power control will be or will becomeapparent to those skilled in the art upon examination of the followingfigures and detailed description. All such additional embodiments,features and advantages are within the scope of the disclosed systemsand methods as defined in the accompanying claims.

BRIEF DESCRIPTION OF THE FIGURES

The adaptive power controller and methods for adaptive power control ina mobile handset can be better understood with reference to thefollowing figures. The components within the figures are not necessarilyto scale, emphasis instead being placed upon clearly illustrating theprinciples and operation of the controller and methods. Moreover, in thefigures, like reference numerals designate corresponding partsthroughout the different views.

FIG. 1 is a block diagram illustrating a simplified mobile handsetincluding a direct launch transmitter.

FIG. 2 is a block diagram illustrating an example embodiment of theadaptive power controller of FIG. 1.

FIG. 3 is a block diagram illustrating an embodiment of the loopbandwidth controller of FIG. 2.

FIG. 4 is a block diagram illustrating an alternative embodiment of theadaptive power controller of FIG. 1.

FIG. 5 is a block diagram illustrating another alternative embodiment ofthe adaptive power controller of FIG. 1.

FIG. 6 is a block diagram illustrating an embodiment of the loopbandwidth controller of FIG. 5.

FIG. 7 is a block diagram illustrating an embodiment of the slopecompensator of FIG. 5.

FIG. 8 is a flow chart illustrating an embodiment of a method foradaptive power control in a mobile handset.

DETAILED DESCRIPTION

Although described with particular reference to a mobile handsetoperating under EDGE, WCDMA, and GMSK communication standards, theadaptive power controller and methods for adaptive power control in amobile handset can be implemented in any communication device wheredynamic power control of a direct launch transmitter is desired.

The adaptive power controller is arranged to accurately track and adjustfor power changes in the transmit output power of the mobile handsetthat are expected to occur with greater frequency than those that can beaccurately tracked and corrected using conventional open-loop powercontrol schemes. The adaptive power controller uses a detector tolocally measure the power level at a power amplifier. An error signal isgenerated as a function of the detected power level and a target powerlevel forwarded from a baseband subsystem. The error signal is processedin a digital signal processor in a RF subsystem of the mobile handset.The digital signal processor can be configured in multiple embodimentsto generate power adjustments that can be applied in near real time inresponse to transmit signal power changes that cannot be tracked andcorrected by the conventional open-loop power control schemes.

In an embodiment illustrated in FIG. 2 and described in further detailbelow, the adaptive controller responds to a transmit power signal asmeasured by a linear detector. The detected transmit power is comparedwith a target power level converted to a voltage to generate an errorsignal. The error signal is applied to a shifter and a scaler thatoperate in accordance with respective bandwidth control signalsgenerated by a loop bandwidth controller to generate a modified errorsignal.

The loop bandwidth controller compensates for the nonlinearity of thegain control characteristics when the target power level exceeds athreshold value to make the loop bandwidth constant over a portion ofthe power control range. A threshold power level of approximately 0 dBmis contemplated. However, the adaptive controller is not so limited andother thresholds may be applied.

An accumulator and a hold element integrate and filter the modifiederror signal to reduce or even eliminate any undesired impact on thetransmit signal error vector magnitude. When the target power level isbelow the threshold value, the adaptive controller applies a code from alook-up table. A control signal responsive to a gain adjust signal andthe target power level is applied to the look-up table to select aparticular code. The selected code is applied at the input of adigital-to-analog converter to generate an analog power control signal.

When the mobile handset is operating in a mode where a dB linearamplifier characteristic is desired, the analog version of the powercontrol signal is applied to a pre-amplifier driver. Otherwise, when themobile handset is operating in a mode where an accurate ramp up and rampdown are desired, the analog version of the power control signal isapplied to the power amplifier gain control input.

In an embodiment illustrated in FIG. 4 and as described in furtherdetail below, the adaptive controller responds to a transmit powersignal as measured by a linear detector. The detected transmit power (avoltage) is mapped into antenna power in dBm using a logarithmicconversion. Alternatively, a logarithmic detector can be used to measurethe transmit power.

The detected transmit power is compared with a target power level in dBmto generate an error signal. The error signal is applied to a shifterand a scaler that operate in accordance with respective bandwidthcontrol signals consisting of a fixed value to generate a modified errorsignal.

The modified error signal is processed by an accumulator (i.e.,integrated) and forwarded to a gain look-up table to identify a selectcode for gain control. The codes in the gain control look-up tablelinearize changes in the dB linear characteristic of the adaptive powercontroller to make the loop bandwidth constant over the entire powercontrol range. A hold element averages or filters the selected codes toreduce or even eliminate any undesired impact on the transmit signalerror vector magnitude. The output of the hold element is applied to adigital-to-analog converter to generate an analog power control signal.

The adaptive controller applies a code from a look-up table when thetarget power level is below the threshold value. A control signalresponsive to a gain adjust signal and the target power level is appliedto the look-up table to select a particular code. The code is applied atthe input of a digital-to-analog converter to generate an analog powercontrol signal.

When the mobile handset is operating in a mode where a dB linearamplifier characteristic is desired, the power control signal is appliedto a pre-amplifier driver. Otherwise, when the mobile handset isoperating in a mode where an accurate ramp up and ramp down are desired,the power control signal is applied to the power amplifier gain controlinput.

In an embodiment illustrated in FIG. 5 and described in further detailbelow, the adaptive controller responds to a transmit power signal asmeasured by a linear detector. The detected transmit power is comparedwith a target power level converted to a voltage to generate an errorsignal. The error signal is applied to a shifter and a scaler thatoperate in accordance with respective bandwidth control signalsgenerated by a loop bandwidth controller to generate a modified errorsignal.

The modified error signal is processed by an accumulator (i.e.,integrated) and forwarded to a multiplexer, which in accordance with aloop mode control signal selects one of a bypass path or a logarithmiccontrol path. The logarithmic control path includes a log converter, asecond shifter and a second scaler. A slope compensator generatesrespective control signals that are applied to the second shifter andthe second scaler, which further process the modified error signal. Asecond multiplexer under the control of the loop mode control signal,selectively forwards the modified error signal from one of the bypasspath or the logarithmic control path to a hold element.

The hold element averages or filters the modified error signal to reduceor even eliminate any undesired impact on the transmit signal errorvector magnitude. For voltage linear gain control characteristics, slopecompensation is applied before the accumulator. For dB linear gaincontrol characteristics, slope compensation is applied after theaccumulator. The adaptive power controller applies bandwidth controls atselect locations to compensate for the nonlinearity of the gain controlcharacteristics when the target power level exceeds a threshold value tomake the loop bandwidth constant over a portion of the power controlrange. A threshold power level of approximately 0 dBm is contemplated.However, the adaptive controller is not so limited and other thresholdsmay be applied.

The adaptive controller applies a code from a look-up table when thetarget power level is below the threshold value. A control signalresponsive to a gain adjust signal and the target power level is appliedto the look-up table to select a particular code. The code is applied atthe input of a digital-to-analog converter to generate an analog powercontrol signal. When the mobile handset is operating in a mode where adB linear amplifier characteristic is desired, the power control signalis applied to a pre-amplifier driver. Otherwise, when the mobile handsetis operating in a mode where an accurate ramp up and ramp down aredesired, the power control signal is applied to the power amplifier gaincontrol input.

The adaptive power controller and methods for adaptive power control ina mobile handset can be implemented in hardware, software, or acombination of hardware and software. When implemented in hardware, theadaptive power controller and methods can be implemented usingspecialized hardware elements and logic. When the adaptive powercontroller and methods are implemented partially in software, thesoftware portion can be used to control one or more components of theadaptive controller so that various operating aspects can be softwarecontrolled. The software can be stored in a memory and executed by asuitable instruction execution system (microprocessor). The hardwareimplementation of the adaptive power controller and methods can includeany or a combination of the following technologies, which are all wellknown in the art: discrete electronic components, a discrete logiccircuit(s) having logic gates for implementing logic functions upon datasignals, an application specific integrated circuit having appropriatelogic gates, a programmable gate array(s) (PGA), a field programmablegate array (FPGA), etc.

The software for the adaptive power controller and methods comprises anordered listing of executable instructions for implementing logicalfunctions, and can be embodied in any computer-readable medium for useby or in connection with an instruction execution system, apparatus, ordevice, such as a computer-based system, processor-containing system, orother system that can fetch the instructions from the instructionexecution system, apparatus, or device and execute the instructions.

In the context of this document, a “computer-readable medium” can be anymeans that can contain, store, communicate, propagate, or transport theprogram for use by or in connection with the instruction executionsystem, apparatus, or device. The computer-readable medium can be, forexample but not limited to, an electronic, magnetic, optical,electromagnetic, infrared, or semiconductor system, apparatus, device,or propagation medium. More specific examples (a non-exhaustive list) ofthe computer-readable medium would include the following: an electricalconnection (electronic) having one or more wires, a portable computerdiskette (magnetic), a random access memory (RAM), a read-only memory(ROM), an erasable programmable read-only memory (EPROM or Flash memory)(magnetic), an optical fiber (optical), and a portable compact discread-only memory (CDROM) (optical). Note that the computer-readablemedium could even be paper or another suitable medium upon which theprogram is printed, as the program can be electronically captured, viafor instance optical scanning of the paper or other medium, thencompiled, interpreted or otherwise processed in a suitable manner ifnecessary, and then stored in a computer memory.

Reference is now directed to example embodiments of the adaptive powercontroller and methods for adaptive power control in a mobile handset asillustrated in the drawings.

FIG. 1 is a block diagram illustrating a mobile handset 100 including adirect launch transmitter 140, which includes an I/Q generator 144, anI/Q controller 142 for initiating ramp power transitions and a RFupconverter 146 for generating a RF transmit signal in the mobilehandset 100. The mobile handset 100 includes an input/output (I/O)element 102 coupled to a baseband subsystem 110 via connection 104. TheI/O element 102 represents any interface with which a user may interactwith the mobile communication device 100. For example, the I/O element102 may include a speaker, a display, a keyboard, a microphone, atrackball, a thumbwheel, or any other user-interface element. A powersource 106, which may be a direct current (DC) battery or other powersource, is also connected to the baseband subsystem 110 via connection108 to provide power to the mobile handset 100. In a particularembodiment, mobile handset 100 can be, for example but not limited to, amobile telecommunication device such as a mobile cellular-typetelephone.

The baseband subsystem 110 includes microprocessor (μP) 120, memory 122,analog circuitry 124, and digital signal processor (DSP) 126 incommunication via bus 128. Bus 128, although shown as a single bus, maybe implemented using multiple busses connected as necessary among thesubsystems within baseband subsystem 110.

Depending on the manner in which the I/Q controller 142 and methods foradaptive power control are implemented, the baseband subsystem 110 mayalso include one or more of an application specific integrated circuit(ASIC), a field programmable gate array (FPGA), or any otherimplementation-specific or general processor.

Microprocessor 120 and memory 122 provide the signal timing, processingand storage functions for the mobile handset 100. Analog circuitry 124provides the analog processing functions for the signals within basebandsubsystem 110. The baseband subsystem 110 provides data and controlsignals to a radio frequency (RF) subsystem 130. The RF subsystem 130receives data from remote transmitters (e.g., base stations) andforwards the received data to the baseband system 110 for furtherprocessing. The RF subsystem 130 includes the direct launch transmitter140, a receiver 170, a pre-amplifier driver 148, and an adaptive powercontroller 200. The elements within the RF subsystem 130 can becontrolled by signals from the baseband subsystem 110 via connection132, which is connected to various baseband elements via bus 128.Alternatively, the direct launch transmitter 140 and the receiver 170may be located on an RF integrated circuit (IC).

The baseband subsystem 110 generates various control signals, such as atarget power signal, a fixed bandwidth control signal, a power amplifiergain adjustment signal, etc. that are used to control the adaptive powercontroller 200. The control signals on connection 132 may originate fromthe DSP 126, the microprocessor 120, or from any other processor withinthe baseband subsystem 110, and are supplied to a variety of connectionswithin the direct launch transmitter 140, receiver 170, and the adaptivepower controller 200. It should be noted that, for simplicity, only thebasic components of the mobile handset 100 are illustrated herein. Thecontrol signals provided by the baseband subsystem 110 control thevarious components within the mobile handset 100.

The adaptive power controller 200 generates a power amplifier (PA) powercontrol signal. The power control signal is coupled to the poweramplifier 152 via connection 205. The power control signal controls thepower output of the power amplifier 152 based on various inputs from thebaseband subsystem 110. For example, in an embodiment, a closed powercontrol loop influences the power output of the power amplifier 152. Inanother embodiment, an open power control loop influences the poweroutput of the power amplifier 152. For example, in an embodiment, asignal received by a base station with which the mobile handset 100 iscommunicating may issue a power control signal. In other embodiments,the baseband subsystem 110 provides loop bandwidth, closed/open loopenable, and various offset signals to the adaptive power controller 200.In turn, the adaptive power controller 200 processes the signals andgenerates a power control signal that is communicated to the poweramplifier 152 on connection 205 or to the pre-amplifier driver 148 onconnection 203.

If portions of the I/Q controller 142 and methods for adaptive powercontrol in a mobile handset 100 are implemented in software that isexecuted by the microprocessor 120, the memory 122 will also includeadaptive power control software 141. The adaptive power control software141 comprises one or more executable code segments that can be stored inthe memory 122 and executed in the microprocessor 120. Alternatively,the functionality of the adaptive power control software 141 can becoded into an ASIC (not shown) or can be executed by an FPGA (notshown), or another device or may be integrated into a transceiver.Because the memory 122 can be rewritable and because a FPGA isreprogrammable, updates to the adaptive power control software 141 canbe remotely sent to and saved in the mobile handset 100 when implementedusing either of these methodologies.

RF subsystem 130 also includes analog-to-digital converter (ADC) 134 andan in-phase quadrature-phase (I/Q) generator 144. In this example, theI/Q generator 144 generates the in-phase (I) and quadrature-phase (Q)signals. The I/Q or transmit signals are forwarded to the RF upconverter146 via connection 145. The ADC 134 and the I/Q generator 144 alsocommunicate with microprocessor 120, memory 122, analog circuitry 124and DSP 126 via bus 128. The I/Q generator 144 converts the digitalcommunication information within baseband subsystem 110 into a digitalsignal for further processing by the RF upconverter 146 for transmissionby the direct launch transmitter 140.

The I/Q generator 144 generator operates in accordance with a controlsignal provided on connection 143 from the I/Q controller 142. The I/Qcontroller 142, operating in accordance with one or more signals on bus132, controllably transfers a modulated I signal and a modulated Qsignal to respective transmit chains and mixers for upconversion to atransmit frequency. The RF upconverter 146 of the direct launchtransmitter 140 combines and transforms the modulated signals to anappropriate transmit frequency and provides the upconverted signal tothe pre-amplifier driver 148 via connection 147. The pre-amplifierdriver 148 controllably amplifies the transmit signal before forwardingthe pre-amplified transmit signal on connection 149 to the poweramplifier module 150. A power amplifier 152 amplifies the transmitsignal to an appropriate power level for the handset given presentconditions under which the mobile handset 100 is operating.

The I and Q components of the transmit signal may take different formsand be formatted differently depending upon the communication standardbeing employed. For example, when the power amplifier module 150 is usedin a constant-amplitude, phase (or frequency) modulation applicationsuch as the global system for mobile communications (GSM), the phasemodulated information is provided by a modulator within the directlaunch transmitter 140. When the power amplifier module 150 is used inan application requiring both phase and amplitude modulation such as,for example, extended data rates for GSM evolution, referred to as EDGE,the Cartesian in-phase (I) and quadrature (Q) components contain bothamplitude and phase information.

The power amplifier module 150 supplies the amplified transmit signalvia connection 153 to a front end module 162. The front end module 162comprises an antenna system interface that may include, for example, adiplexer having a filter pair that allows simultaneous passage of bothtransmit signals and receive signals, as known to those having ordinaryskill in the art. The transmit signal is supplied from the front endmodule 162 to the antenna 165.

A signal received by the antenna 165 is directed from the front endmodule 162 to the receiver 170 on connection 163. The receiver 170includes various components to downconvert, filter, demodulate andrecover a data signal from a received signal, as known to those skilledin the art. If implemented using a direct conversion receiver (DCR), thereceiver 170 converts the received signal from an RF level to a basebandlevel (DC), or a near-baseband level (˜100 kHz). Alternatively, thereceived RF signal may be downconverted to an intermediate frequency(IF) signal, depending on the system architecture. The recoveredtransmitted information is supplied via connection 180 to the ADC 134.The ADC 134 converts these analog signals to a digital signal atbaseband frequency and transfers the signal via bus 128 to DSP 126 forfurther processing.

FIG. 2 is a block diagram illustrating an example embodiment of theadaptive power controller 200 of FIG. 1. The combination of the poweramplifier module 150 and the adaptive power controller 200 forms closedand open power control loops for adjusting transmit power levels in nearreal time. The adaptive power controller 200 receives multiple signalsfrom the baseband subsystem 110 that direct the adaptive powercontroller 200 to apply one of a closed control loop or an open controlloop within the RF subsystem 130 of the handset. The adaptive powercontroller 200 receives a communication mode control signal onconnection 201, a voltage offset signal on connection 202, a closed/openloop control signal on connection 204, a target power level in dB onconnection 206, and a power amplifier gain adjust signal on connection208. In response, the adaptive power controller 200 generates an analogpower control signal.

The detector 154 within the power amplifier module 150 forwards adetected transmit power signal on connection 155 to preamp 210, whichbuffers and amplifies the detected transmit power signal beforeforwarding the signal on connection 211 to an analog-to-digitalconverter (ADC) 212. The ADC 212 converts the analog voltage to adigital signal and forwards the same on connection 213 to the digitalgain control element (DGC) 214. The DGC 214 scales and forwards thedigital version of the detected transmit power on connection 215 to theadder 216. The adder 216 subtracts the voltage offset signal onconnection 202 from the digital version of the detected transmit powersignal and forwards the result on connection 217 to the adder 218.

The target power level received on connection 206 is converted from alog value (in dBm) to a linear unit (volts) by the power to voltageconverter 220, which forwards the result on connection 221 to the adder218. The adder 218 subtracts the detected and offset adjusted transmitpower signal from the target power level in volts to generate an errorsignal, which is forwarded on connection 223 to a right shifter 224.

As illustrated in FIG. 2, the target power level received on connection206 is coupled to a loop bandwidth controller 300 that generates a firstbandwidth control, which is forwarded on connection 226 to a controlinput of the right shifter 224. In addition, the loop bandwidthcontroller 300 generates a second bandwidth control signal, which isforwarded to a scaler 228 on connection 227. The right shifter processesthe error signal in accordance with the first bandwidth control signaland forwards the shifted error signal on connection 225 to the scaler228. The scaler 228 adjusts the shifted error signal in accordance withthe second bandwidth control signal to generate a modified error signal,which is forwarded to the accumulator 230 on connection 229. Theaccumulator 230 integrates the modified error signal and forwards theresult on connection 231 to the hold element 232. The hold element 232filters or averages the integrated version of the modified error signaland forwards the result on connection 233 to a first data input of themultiplexer 234.

When directed by the closed/open loop signal on connection 204 tooperate in a closed loop, that is when the target power level exceeds apredetermined threshold value, the multiplexer 234 forwards theintegrated and filtered version of the modified error signal onconnection 235 to the digital-to-analog converter (DAC) 236. The DAC 236converts the integrated and filtered version of the modified errorsignal to generate an analog power control signal, which is forwarded onconnection 237 to the low-pass filter (LPF) 238. The LPF 238 reduces oreliminates high-frequency signal components that may be present in thepower control signal before forwarding the filtered power control signalon connection 239 to the switch 240. As indicated in FIG. 2, the switch240 directs the power control signal to the pre-amplifier driver 148 onconnection 203 when the communication mode control signal on connection201 indicates that the handset is operating under an EDGE/WCDMAcommunication mode. Otherwise, the switch 240 directs the power controlsignal to the power amplifier 150 on connection 205 when thecommunication mode control signal on connection 201 indicates that thehandset of operating under a GMSK communication mode.

The adaptive power controller 200 receives the target power level onconnection 206 and a power amplifier gain adjust control signal onconnection 208 which are coupled to the inputs of the adder 242. Thepower amplifier gain adjust control signal received from the basebandsubsystem 110 is responsive to one or both of a present temperature anda desired transmit frequency band of the handset. The adder 242generates and forwards a combined signal which is applied at an indexinput of the gain look-up table 250. In turn the gain look-up tableforwards a code on connection 251 to a second data input of themultiplexer 234. When the target power level is below the thresholdvalue, the closed/open loop control signal on connection 204, directsthe multiplexer 234 to forward the code on connection 235 to the DAC236. In this open loop mode of operation, the code as converted by theDAC 236 becomes the power control signal that is low-pass filtered andforwarded to one of the pre-amplifier driver 148 or the power amplifier150 as described above. The closed-loop adaptive bandwidth controlillustrated and described above in association with FIG. 2, isresponsive to a voltage representation of the transmit power level. Thecontrol scheme permits the re-use of the closed-loop components for bothWCDMA and EDGE/GMSK communication standards. The proposed scheme is alsosuitable for providing a full range of transmit power control as well ascontrolled power ramp-up and ramp-down transitions in EDGE/GMSK mode.

FIG. 3 is a block diagram illustrating an embodiment of the loopbandwidth controller 300 of FIG. 2. The loop bandwidth controller 300receives multiple signals from the baseband subsystem 110 that directthe loop bandwidth controller 300 to apply one of a target power inputfrom a ramp processor of the handset or a second generation or 2Gantenna power when generating appropriate bandwidth control signals forapplication in the closed loop of the adaptive power controller 200 ofFIG. 2. The loop bandwidth controller 300 receives the target power onconnection 301, a transmit enable signal on connection 302, a 2G antennapower signal on connection 303, and a band/mode select input signal onconnection 305. In addition to these inputs, the loop bandwidthcontroller applies a maximum transmit power or P_(H) on connection 306and a minimum power or P_(L) on connection 304. In response, the loopbandwidth controller 300 generates and forwards a first bandwidthcontrol signal on connection 226 and a second bandwidth control signalon connection 227. As described above, the first bandwidth controlsignal is coupled to a control input of the right shifter 224 and thesecond bandwidth control signal is coupled to a control input of thescaler 228.

When the transmit enable signal on connection 302 directs the switch 307to apply the target power level on connection 301, the switch 307forwards the target power signal on connection 325 to the adder 326.When the transmit signal on connection 302 directs the switch 307 toapply the 2G antenna power on connection 303, the switch 307 forwardsthe 2G antenna power on connection 325 to the adder 326.

The adder 326 is also arranged to receive the minimum transmit powerlevel on connection 304. The adder 326 forwards the difference of thetarget power level and the minimum transmit power level on connection327 to the indexer 328. The indexer 328 processes the receiveddifference signal and generates an index control signal that isforwarded on connection 329 to the look-up table 330. The look-up table330, in response to the index control signal and the band/mode selectsignal on connection 305, identifies a select entry in the table andforwards a normalized DAC slope on connection 341 to the scaler 320.

The target power level on connection 306 and the maximum transmit powerlevel on connection 306 are coupled to the adder 308. The adder forwardsthe sum of the received values on connection 309 to the scaler 310. Notethat additional circuitry will be needed to ensure that the output ofthe adder 308 is a positive number when the target power is provided indBm. The scaler 310 scales the sum of the target power received from theramp processor of the handset with the maximum transmit power togenerate and forward a digital representation of a real number onconnection 311. An integer element or INT 322 receives the real numberon connection 311 and forwards the integer portion of the number onconnection 226. The integer portion of the real number is the firstbandwidth control signal. A fractional element or FRAC 312 receives thereal number on connection 311 and forwards a representation of thefractional portion thereof on connection 313 to the approximator 314.The approximator 314 uses an approximation process to adjust thefractional portion of the real number to generate a scaler controlsignal that is forwarded on connection 315 to the scaler 320. In turn,the scaler 320 applies the scaler control signal to generate a scaledversion of the normalized DAC slope which is forwarded on connection 227to the scaler 228 in the closed control loop of the adaptive powercontroller 200 (FIG. 2). The scaled version of the normalized DAC slopeis the second bandwidth control signal.

FIG. 4 is a block diagram illustrating an alternative embodiment of theadaptive power controller of FIG. 1. The combination of the poweramplifier module 150 and the adaptive power controller 400 forms closedand open power control loops for adjusting transmit power levels in nearreal time. The adaptive power controller 400 receives multiple signalsfrom the baseband subsystem 110 that direct the adaptive powercontroller 400 to apply one of a closed control loop or an open controlloop within the RF subsystem 130 of the handset. The adaptive powercontroller 400 receives a communication mode control signal onconnection 201, a voltage offset signal on connection 202, a dB offsetsignal on connection 402, a closed/open loop control signal onconnection 404, a target power level in dB on connection 406, and apower amplifier gain adjust signal on connection 208. In response, theadaptive power controller 400 generates an analog power control signalthat is controllably applied at the pre-amplifier driver 148 or the atthe power amplifier 152.

The detector 154 within the power amplifier module 150 forwards adetected transmit power signal on connection 155 to preamp 210, whichbuffers and amplifies the detected transmit power signal beforeforwarding the signal on connection 211 to an analog-to-digitalconverter (ADC) 212. The ADC 212 converts the analog voltage to adigital signal and forwards the same on connection 213 to the digitalgain control element (DGC) 214. The DGC 214 scales and forwards thedigital version of the detected transmit power on connection 215 to theadder 216. The adder 216 subtracts the voltage offset signal onconnection 202 from the digital version of the detected transmit powersignal and forwards the result on connection 408 to the RMS element 410which generates a root-mean square representation of the detectedtransmit power and forwards the same on connection 415 to dBm converter420. The dBm converter 420 converts the signal on connection 415(representing a voltage) using a log conversion to generate detectedtransmit power in dBm. The dBm converter 420 forwards the result onconnection 425 to the adder 430, which subtracts the dB offset signalreceived on connection 402. The adder 430 forwards the result onconnection 433 to the adder 434.

The target power level received on connection 406 is coupled to theother input of the adder 434, which subtracts the detected transmitpower from the target power level signal and forwards an error signal onconnection 223 to a right shifter 224. In the illustrated embodiment, afixed bandwidth control signal is coupled on connection 226 to a controlinput of the right shifter 224 as well as to the scaler 228. The rightshifter 224 processes the error signal in accordance with the fixedbandwidth control signal (BW control) and forwards the shifted errorsignal on connection 225 to the scaler 228. The scaler 228 adjusts theshifted error signal in accordance with the fixed bandwidth controlsignal to generate a modified error signal, which is forwarded to theaccumulator 230 on connection 229. The accumulator 230 integrates themodified error signal and forwards the result on connection 231 to themultiplexer 434. The multiplexer 434 receives the target power signal onconnection 406 and forwards one of the target power signal or themodified and integrated error signal on connection 435 in accordancewith the closed/open loop control signal on connection 404.

When directed by the closed/open loop signal on connection 404 tooperate in a closed loop, that is when the target power level exceeds apredetermined threshold value, the multiplexer 434 forwards theintegrated and filtered version of the modified error signal onconnection 435 to the adder 242, the adder 242 also receives a poweramplifier gain adjust control signal on connection 208. The poweramplifier gain adjust control signal received from the basebandsubsystem 110 is responsive to one or both of a present temperature anda desired transmit frequency band of the handset. The adder 242generates and forwards a combined signal on connection 243 which is usedas an index to identify a code in the gain look-up table 250. The gainlook-up table 250 linearizes changes in the dB linear controlcharacteristic within the adaptive power controller 400 to make the loopbandwidth constant over the entire power control range.

The gain look-up table forwards a combination of the gain adjustedmodified error signal via connection 436 to the hold element 232, whichaverages the combined signal on connection 437 to the DAC 236. The DAC236 converts the integrated and filtered version of the modified errorsignal to generate an analog power control signal, which is forwarded onconnection 237 to the low-pass filter (LPF) 238. The LPF 238 reduces oreliminates high-frequency signal components that may be present in thepower control signal before forwarding the filtered power control signalon connection 239 to the switch 240. As indicated in FIG. 2, the switch240 directs the power control signal to the pre-amplifier driver 148 onconnection 203 when the communication mode control signal on connection201 indicates that the handset is operating under an EDGE/WCDMAcommunication mode. Otherwise, the switch 240 directs the power controlsignal to the power amplifier 150 on connection 205 when thecommunication mode control signal on connection 201 indicates that thehandset of operating under a GMSK communication mode.

When the target power level is below the threshold value, theclosed/open loop control signal on connection 404, directs themultiplexer 434 to forward the target power signal on connection 406 onconnection 435 to the adder 242, where it is combined with the poweramplifier gain adjustment signal received on connection 208. In thiscase, the gain adjusted target power signal on connection 243 is used asan index to select a code form the gain look-up table 250. Furtherprocessing of the select code in generating the power control signaloccurs as described above.

The closed-loop adaptive bandwidth control illustrated and describedabove in association with FIG. 4, is responsive to a voltagerepresentation of the transmit power level. Alternatively, a logdetector could be used to replace the detector 154. When a log detectoris used, the log conversion performed by the dBm converter 420 is notrequired. The control scheme permits the re-use of the closed-loopcomponents for both WCDMA and EDGE/GMSK communication standards. Theproposed scheme is also suitable for providing a full range of transmitpower control as well as controlled power ramp-up and ramp-downtransitions in EDGE/GMSK mode.

FIG. 5 is a block diagram illustrating another alternative embodiment ofthe adaptive power controller of FIG. 1. The combination of the poweramplifier module 150 and the adaptive power controller 500 forms closedand open power control loops for adjusting transmit power levels in nearreal time. The adaptive power controller 500 receives multiple signalsfrom the baseband subsystem 110 that direct the adaptive powercontroller 500 to apply one of a closed control loop or an open controlloop within the RF subsystem 130 of the handset. The adaptive powercontroller 500 receives a communication mode control signal onconnection 201, a voltage offset signal on connection 202, a closed/openloop control signal on connection 204, a target power level in dB onconnection 206, a power amplifier gain adjust signal on connection 208,and a loop mode control signal on connection 505. In response, theadaptive power controller 500 generates an analog power control signalthat is controllably applied at the pre-amplifier driver 148 or the atthe power amplifier 152.

The detector 154 within the power amplifier module 150 forwards adetected transmit power signal on connection 155 to preamp 210, whichbuffers and amplifies the detected transmit power signal beforeforwarding the signal on connection 211 to the ADC 212. The ADC 212converts the analog voltage to a digital signal and forwards the same onconnection 213 to the DGC 214. The DGC 214 scales and forwards thedigital version of the detected transmit power on connection 215 to theadder 216. The adder 216 subtracts the voltage offset signal onconnection 202 from the digital version of the detected transmit powersignal and forwards the result on connection 217 to the adder 218.

The target power level received on connection 206 is converted from alog value (in dBm) to a linear unit (volts) by the power to voltageconverter 220, which forwards the result on connection 221 to the adder218. The adder 218 subtracts the detected and offset adjusted transmitpower signal from the target power level in volts to generate an errorsignal, which is forwarded on connection 223 to a right shifter 224.

As illustrated in FIG. 5, the target power level received on connection206 is coupled to a loop bandwidth controller 600 that generates a firstbandwidth control, which is forwarded on connection 226 to a controlinput of the right shifter 224. In addition, the loop bandwidthcontroller 600 generates a second bandwidth control signal, which isforwarded to a scaler 228 on connection 227. The loop bandwidthcontroller 600 is further described in association with the embodimentillustrated in FIG. 6.

The right shifter processes the error signal in accordance with thefirst bandwidth control signal and forwards the shifted error signal onconnection 225 to the scaler 228. The scaler 228 adjusts the shiftederror signal in accordance with the second bandwidth control signal togenerate a modified error signal, which is forwarded to the accumulator230 on connection 229. The accumulator 230 integrates the modified errorsignal and forwards the result on connection 231 to the multiplexer 520.

The multiplexer 520 and the multiplexer 550 operate under the control ofthe loop mode signal on connection 505. When a dB linear controlcharacteristic is desired, the loop mode signal directs the multiplexer520 to forward the modified error signal through the elements of alogarithmic control path 530. Otherwise, when a voltage linear controlcharacteristic is desired, the loop mode signal directs the multiplexer520 to forward the modified error signal on connection 540, whichbypasses the logarithmic control path 530. The multiplexer 550 inaccordance with the loop mode control signal on connection 505,controllably forwards the output of one of the logarithmic control path530 or the bypass path (i.e., the modified error signal connection 540)on connection 555 to the hold element 232.

The logarithmic control path 530 includes a series arrangement of a logconverter 532, a right shifter 534 and a multiplier 536. The rightshifter 534 receives a third bandwidth control signal on connection 702from the slope compensator 700. The multiplier 536 receives a fourthbandwidth control signal on connection 704 from the slope compensator700. The slope compensator 700 is further described in association withthe embodiment illustrated in FIG. 7. The right shifter 534 processesthe modified error signal in accordance with the third bandwidth controlsignal and forwards the shifted and modified error signal to themultiplier 536. The multiplier 536 adjusts the shifted and modifiederror signal in accordance with the second bandwidth control signal togenerate a modified error signal, which is forwarded to the hold element232 via the multiplexer 550 and connection 555. The hold element 232filters or averages the integrated and slope compensated version of themodified error signal and forwards the result on connection 233 to afirst data input of the multiplexer 234.

When directed by the closed/open loop signal on connection 204 tooperate in a closed loop, that is when the target power level exceeds apredetermined threshold value, the multiplexer 234 forwards theintegrated, slope compensated, and filtered version of the modifiederror signal on connection 235 to the DAC 236. The DAC 236 converts theintegrated, slope compensated, and filtered version of the modifiederror signal to generate an analog power control signal, which isforwarded on connection 237 to the LPF 238. The LPF 238 reduces oreliminates high-frequency signal components that may be present in thepower control signal before forwarding the filtered power control signalon connection 239 to the switch 240. As indicated in FIG. 5, the switch240 directs the power control signal to the pre-amplifier driver 148 onconnection 203 when the communication mode control signal on connection201 indicates that the handset is operating under an EDGE/WCDMAcommunication mode. Otherwise, the switch 240 directs the power controlsignal to the power amplifier 150 on connection 205 when thecommunication mode control signal on connection 201 indicates that thehandset of operating under a GMSK communication mode.

The adaptive power controller 500 receives the target power level onconnection 206 and a power amplifier gain adjust control signal onconnection 208 which are coupled to the inputs of the adder 242. Thepower amplifier gain adjust control signal received from the basebandsubsystem 110 is responsive to one or both of a present temperature anda desired transmit frequency band of the handset. The adder 242generates and forwards a combined signal which is applied at an indexinput of the gain look-up table 250. In turn, the gain look-up tableforwards a code on connection 251 to a second data input of themultiplexer 234. When the target power level is below the thresholdvalue, the closed/open loop control signal on connection 204, directsthe multiplexer 234 to forward the code on connection 235 to the DAC236. In this open loop mode of operation, the code as converted by theDAC 236 becomes the power control signal that is low-pass filtered andforwarded to one of the pre-amplifier driver 148 or the power amplifier150 as described above.

The closed-loop adaptive bandwidth control illustrated and describedabove in association with FIG. 5, is responsive to a voltagerepresentation of the transmit power level. The control scheme permitsthe re-use of the closed-loop components for both WCDMA and EDGE/GMSKcommunication standards. The proposed scheme is also suitable forproviding a full range of transmit power control as well as controlledpower ramp-up and ramp-down transitions in EDGE/GMSK mode. The bandwidthcontrol signals are applied in two different locations to compensate forthe nonlinearity of the gain control characteristics to make the loopbandwidth constant over the entire power control range. For voltagelinear gain control characteristics, the slope compensation is appliedbefore the accumulator 230. For dB linear control characteristics, slopecompensation is applied after a log conversion.

FIG. 6 is a block diagram illustrating an embodiment of the loopbandwidth controller 600 of FIG. 5. The loop bandwidth controller 600receives multiple signals from the baseband subsystem 110 that directthe loop bandwidth controller 600 to apply a loop bandwidth constant anda target power when generating appropriate bandwidth control signals forapplication in the closed loop of the adaptive power controller 500 ofFIG. 5. The loop bandwidth controller 600 receives the loop bandwidthconstant on connection 601, a loop mode select signal on connection 602,a post bypass bit on connection 604, the target power on connection 605,and a band select input signal on connection 306. In addition to theseinputs, the loop bandwidth controller 600 applies a minimum power orX_(min) on connection 304 and a constant K on connection 609. Inresponse, the loop bandwidth controller 600 generates and forwards afirst bandwidth control signal on connection 226 and a second bandwidthcontrol signal on connection 227. As described above, the firstbandwidth control signal is coupled to a control input of the rightshifter 224 and the second bandwidth control signal is coupled to acontrol input of the scaler 228.

The adder 610 is arranged to receive the target power in volts onconnection 605 and the minimum transmit power level on connection 603.The adder 610 forwards the difference of the target power level and theminimum transmit power level on connection 611 to the scaler 612. Thescaler 612 scales the difference of the target power level and theminimum transmit power level and forwards the result on connection 613to the indexer 614. The indexer 614 processes the received signal andgenerates an index control signal that is forwarded on connection 615 tothe look-up table 620. The look-up table 620, in response to the indexcontrol signal and the band select signal on connection 606, identifiesa select entry in the table and forwards a GMSK normalized DAC slope onconnection 621 to a first data input of the multiplexer 632. Themultiplexer 632 receives a binary 1 on its second data input. The postbypass bit signal 604 is inverted by inverter 630 and coupled to thecontrol input of the multiplexer 632 via connection 631. In accordancewith the signal on connection 631, the multiplexer 632 forwards one ofthe binary 1 or the GMSK normalized DAC slope value on connection 633which is coupled to a first data input of the multiplexer 634. A seconddata input of the multiplexer 634 is arranged to receive the binary 1 onits second data input. In accordance with the loop mode select inputsignal on connection 602, the multiplexer 634 forwards one of the signalon connection 633 or the binary 1 on connection 635 to the scaler 650.When it is desired to correct the bandwidth for a dB linear controlcharacteristic, the binary 1 is forwarded to the scaler 650.

The loop bandwidth constant on connection 601 and the constant K onconnection 609 are coupled to the adder 640. The adder 640 forwards thesum of the received values on connection 641 to the scaler 642. Thescaler 642 scales the sum of the loop bandwidth constant and K togenerate and forward a digital representation of a real number onconnection 643. An integer element or INT 652 receives the real numberon connection 643 and forwards the integer portion of the number onconnection 653 to the adder 654. The adder 654 receives an integer M onconnection 657 and forwards the difference of the integer M and theinteger portion of the real number on connection 226. The difference ofthe integer M and the integer portion of the real number is the firstbandwidth control signal. A fractional element or FRAC 644 receives thereal number on connection 643 and forwards a representation of thefractional portion thereof on connection 645 to the adder 646. The adderreceives a binary 1 on connection 607. The sum of the fractional portionof the real number and the binary 1 is forwarded via connection 647 tothe scaler 650. In turn, the scaler 650 generates a scaled version ofthe GMSK normalized DAC slope or the binary 1. The scaled output signalis forwarded on connection 227 to the scaler 228 in the closed controlloop of the adaptive power controller 500 (FIG. 5). The scaled outputsignal is the second bandwidth control signal.

FIG. 7 is a block diagram illustrating an embodiment of the slopecompensator 700 of FIG. 5. The slope compensator 700 receives multiplesignals from the baseband subsystem 110 that direct the slopecompensator to generate appropriate bandwidth control signals forapplication in the closed loop of the adaptive power controller 500 ofFIG. 5. The slope compensator 700 receives a band/mode select signal onconnection 701, a target power level signal on connection 703 and a loopmode select signal on connection 705. In addition to these inputs, theslope compensator 700 600 applies a minimum power or X_(min) onconnection 702 and first and second constants on connection 707 andconnection 709, respectively. In response, the slope compensator 700generates and forwards a third bandwidth control signal on connection702 and a fourth bandwidth control signal on connection 704. Asdescribed above, the third bandwidth control signal is coupled to acontrol input of the right shifter 534 and the fourth bandwidth controlsignal is coupled to a control input of the scaler 536.

In accordance with the loop mode select signal on connection 705, themultiplexer 760 controllably forwards one of the first and secondconstants on connection 762, which is coupled to the control inputs ofshifter 714, shifter 736, and shifter 754. The shifter 714, the shifter736, and the shifter 754 controllably forward through the slopecompensator 700 in the process of generating the third bandwidth controlsignal on connection 702 and the fourth bandwidth control signal onconnection 704.

The adder 710 receives the target power (in dBm) on connection 703 and aminimum transmit power on connection 702. The slope compensator 700subtracts the minimum transmit power from the target power level andforwards the result on connection 712 to the shifter 714. The shifter714 processes the result and forwards a shifted version of the same onconnection 716 to the integer element 718. The integer element 718forwards the integer portion of the signal on connection 716 to theshifter 754, the look-up table 730 and the look-up table 734 viaconnection 720. The look-up table 730 is actually several tables thatoperate under the control of the band/mode select input 701 and theoutput of the integer element 718. The look-up table 730 includes DACslope values, a select one of which is forwarded on connection 732 tothe shifter 736. The shifter 736 forwards the processed DAC slope valueon connection 738 to the scaler 740. The scaler 740 generates a firstscaled signal which is forwarded on connection 742 to a first data inputof the multiplexer 750. In addition, the scaler 740 generates a secondscaled signal, different in magnitude from the first scaled signal,which is forwarded on connection 746 to a second data input of themultiplexer 750. The multiplexer 750 forwards one of the first scaledsignal or the second scaled signal on connection 702 in accordance withthe loop mode select signal on connection 705.

As indicated in FIG. 7, the connection 702 is also coupled to thecontrol input of the scaler 770. The adder 764 adds the minimum transmitpower received on connection 702 with the shifted version of the integerportion of the difference between the target power and the minimumtransmit power received on connection 756 and forwards the result onconnection 766 to the scaler 770. The scaler 770 adjusts the signal onconnection 766 in accordance with the third bandwidth control signalreceived on connection 702 and forwards the result on connection 772 tothe adder 764. The look-up table 734 is actually several tables thatoperate under the control of the band/mode select input 701 and theoutput of the integer element 718. The look-up table 734 includes DACoffset values, a select one of which is forwarded on connection 735 tothe adder 764. The adder 764 sums the DAC offset value with the scaledsignal on connection 772 and forwards the result on connection 704. Theresult on connection 704 is the fourth bandwidth control signal.

FIG. 8 is a flow chart illustrating the operation of an embodiment of amethod for adaptive power control in a mobile handset transmitter. Theflow diagram of FIG. 8 shows the architecture, functionality, andoperation of a possible implementation via software and or firmwareassociated with an adaptive power controller arranged with a directlaunch transmitter. In this regard, a block can represent a module,segment, or portion of code, which comprises one or more executableinstructions for implementing the specified function(s). When theadaptive power controller is implemented via hardware, hardware andfirmware or a combination of hardware and software, one or more blocksin the flow diagram may represent a circuit or circuits forming anelement. Alternatively, the described functions can be embodied insource code including human-readable statements written in a programminglanguage or machine code that comprises instructions recognizable by asuitable execution system such as a processor in a computer system. Themachine code may be converted from the source code, etc.

Method 800 begins with block 802 where a power detector is used todetect an output power level generated by a power amplifier in a mobilehandset. Next, as indicated in block 804, an error signal is generatedin response to a function of a target power level and the output powerlevel in a radio frequency sub-system of the mobile handset. Thereafter,as shown in block 806, a bandwidth control signal is applied to theerror signal to generate a modified error signal in a closed controlloop of an adaptive power controller in the mobile handset. As furtherindicated in block 806, in response to a desired range of transmitpower, the adaptive power controller controllably forwards one of themodified error signal or a code to generate a power control signal. Asexplained above, when the mobile handset is operating in one of an EDGEor WCDMA mode (i.e., modes where dB linear amplification is desired totrack the changing transmit power level), the power control signal isforwarded to a pre-amplifier driver, which amplifies the transmit signalbefore forwarding the pre-amplified transmit signal to the poweramplifier. Otherwise, when the mobile handset is operating in a GMSKmode (i.e., a mode where a well controlled transmit power ramp up andramp down is desired), the power control signal is forwarded to thepower amplifier. As also explained above, when the target transmit poweras provided by a power target input signal from the baseband subsystemis less than a desired threshold, the adaptive power controller isconfigured to apply the target power input signal to a gain controllook-up table to select an appropriate code to apply at the input to adigital to analog converter to generate the power control signal.

While various embodiments of the adaptive power controller and methodsfor adaptive power control in a mobile handset have been described, itwill be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof this disclosure. Accordingly, the adaptive power controller andmethods are not to be restricted except in light of the attached claimsand their equivalents.

What is claimed is:
 1. A method for adaptive bandwidth control in amobile handset transmitter, comprising: using a power detector to detectan output power level generated by a power amplifier; generating anerror signal responsive to a target power level and the output powerlevel in a radio frequency sub-system of the mobile handset; andapplying a bandwidth control signal to the error signal to generate amodified error signal in a closed control loop of an adaptive powercontroller in the mobile handset, the adaptive power controllercontrollably forwarding one of the modified error signal or a code togenerate a power control signal in response to a desired range oftransmit power, the adaptive power controller including a first shifterand a first scaler, said applying the bandwidth control signal to theerror signal including applying a logarithmic control path to a filterederror signal, the logarithmic control path including a log converter, asecond shifter, and a second scaler, the logarithmic control pathresponsive to a slope compensator coupled to the second shifter and thesecond scaler.
 2. The method of claim 1 wherein generating the errorsignal responsive to the target power level includes converting theoutput power level from a linear scale to a logarithmic scale.
 3. Themethod of claim 1 wherein applying the bandwidth control signal to theerror signal to generate the modified error signal includes applying aloop bandwidth controller responsive to the target power level, the loopbandwidth controller operating in a first mode of operation or a secondmode of operation in response to a transmit enable signal.
 4. The methodof claim 1 wherein generating the error signal responsive to the targetpower level and the output power level includes generating a logarithmicvalue and applying the bandwidth control signal to the error signal togenerate the modified error signal includes applying a constantlogarithmic value to elements within the closed control loop.
 5. Themethod of claim 4 wherein controllably forwarding the code includessending a value from a look-up table in the closed control loop.
 6. Themethod of claim 1 wherein generating the error signal responsive to thetarget power level includes converting the target power level from alogarithmic scale to a linear scale.
 7. The method of claim 6 whereincontrollably forwarding the code to generate the power control signalincludes sending a value from a look-up table outside the closed controlloop.
 8. The method of claim 1 wherein controllably forwarding one ofthe modified error signal or the code includes forwarding the code whenthe target power level is less than a desired threshold value.
 9. Themethod of claim 1 wherein controllably forwarding one of the modifiederror signal or the code includes forwarding the modified error signalwhen the target power level is greater than a desired threshold value.10. The method of claim 1 further comprising applying an accumulator tothe modified error signal to generate an integrated error signal. 11.The method of claim 1 wherein the slope compensator is responsive to atransmit mode and a frequency band.
 12. The method of claim 11 whereinthe slope compensator is responsive to the target power level and aminimum power level.
 13. The method of claim 1 wherein applying thebandwidth control signal to the error signal to generate the modifiederror signal includes applying a loop bandwidth controller that receivesthe target power level in a logarithmic unit and forwards the bandwidthcontrol signal in a linear unit.
 14. The method of claim 13 wherein theloop bandwidth controller is responsive to a loop bandwidth constant.15. The method of claim 1 further comprising controllably applying thepower control signal to a pre-amplifier driver when communicating viaEDGE and WCDMA communication standards and to a power amplifier whencommunicating via GMSK.
 16. A mobile handset, comprising: a poweramplifier module including a power amplifier and a power detector, thepower amplifier arranged to receive a transmit signal and a powercontrol signal and generate an amplified transmit signal, the powerdetector configured to generate a detector output responsive to theamplified transmit signal power; an adaptive power controller coupled tothe power amplifier module, the adaptive power controller forming aclosed control loop with the power amplifier module, the adaptive powercontroller including a first shifter, a first scaler, an accumulator anda hold element, the first shifter and the first scaler being arranged toreceive a bandwidth control signal and in combination generate amodified error signal responsive to an error signal generated from atarget power level and the detector output, the accumulator and holdelement filtering the modified error signal to generate the powercontrol signal; and a logarithmic control path inserted in the closedloop between the accumulator and the hold element, the logarithmiccontrol path including a log converter, a second shifter, a secondscaler, the logarithmic control path responsive to a slope compensatorcoupled to the second shifter and the second scaler.
 17. The handset ofclaim 16 further comprising a loop bandwidth controller arranged toreceive the target power level and generate a first control signal and asecond control signal, the first control being applied to a firstshifter control input and the second control signal being applied to afirst scaler control input.
 18. The handset of claim 17 wherein the loopbandwidth controller receives a loop bandwidth constant.
 19. The handsetof claim 16 wherein the first shifter and the first scaler receive abandwidth control signal that is fixed in value.
 20. A RF subsystemcomprising: a power amplifier module including a power amplifier and apower detector, the power amplifier arranged to receive a transmitsignal and a power control signal and generate an amplified transmitsignal, the power detector configured to generate a detector outputresponsive to the amplified transmit signal power; an adaptive powercontroller coupled to the power amplifier module, the adaptive powercontroller forming a closed control loop with the power amplifiermodule, the adaptive power controller including a first shifter, a firstscaler, an accumulator and a hold element, the first shifter and thefirst scaler being arranged to receive a bandwidth control signal and incombination generate a modified error signal responsive to an errorsignal generated from a target power level and the detector output, theaccumulator and hold element filtering the modified error signal togenerate the power control signal; and a logarithmic control pathinserted in the closed loop between the accumulator and the holdelement, the logarithmic control path including a log converter, asecond shifter, a second scaler, the logarithmic control path responsiveto a slope compensator coupled to the second shifter and the secondscaler.